[llvmlinux] ARM -mfpu=-softvfp+vfp

Behan Webster behanw at converseincode.com
Wed Feb 19 18:19:48 UTC 2014


I probably should have Cc-ed Olof as well.

On 02/19/14 10:16, Behan Webster wrote:
> Cc-ing Arnd Bergmann as he is relevant to this discussion.
>
> On 02/19/14 03:18, Renato Golin wrote:
>> Folks,
>>
>> Following bug:
>>
>> http://llvm.org/bugs/show_bug.cgi?id=18689
>>
>> I think the fix for the second problem (softvfp) is *also* to change
>> the compilation flags.
>>
>> The rationale is in Bernie's email:
>>
>> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140217/099354.html 
>>
>>
>> Mainly that "softvfp+vfp" is ambiguous in many different ways and
>> implementing it would be promoting differences between the compilers,
>> rather than bringing them back together.
>>
>> Also, we need first to ask what do GAS need to know about the PCS? Is
>> this just something that unknowingly got in for the Android build?
>> Does that flag really needs to be passed in that way, or can it be
>> just -Wa,-mfpu=vfp + -mfloat-abi=softfp? That has the same behaviour
>> on the compiler and is supported by both LLVM and GCC.
> Arnd Bergman is likely the right person to ask about the flags set in 
> arch/arm/vp/Makefile
>
> KBUILD_AFLAGS :=$(KBUILD_AFLAGS:-msoft-float=-Wa,-mfpu=softvfp+vfp 
> -mfloat-abi=soft)
>
> Would there be issues in changing the flags to -Wa,-mfpu=vfp 
> -mfloat-abi=softfp?
>
> Behan
>


-- 
Behan Webster
behanw at converseincode.com



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